Last week, we brought you the story of a new NASA drone called Vanilla that is being used to measure the snow depth on top of Arctic ice. Understanding the depth of that snow means that we can remove it from satellite data on the thickness of the ice itself, leading to more accurate measurements. While NASA has been testing out their new drone, a team of scientists has used, for the first time, the combined data from lidar and radar satellites to do the same task.

The lidar satellite ICESat-2 and the radar satellite CryoSat-2 data were combined to estimate the snow depth as well as the height of the exposed sea ice that is above the waterline. The researchers analyzed the data and found that the volume of Arctic sea ice has decreased by 16% of its winter amount in just three years, losing about half a meter of thickness.

That’s not good. Lead author Sahra Kacimi also points out: We weren’t really expecting to see this decline, for the ice to be this much thinner in just three short years.

Again, here is why the snow depth is important. Snow is heavy, and the more it accumulates, the more it can weigh down sea ice, decreasing the amount that is above the waterline. Comparisons to climate records from previous studies show that the snow depth was being overestimated by about 20% or 0.2 meters. Co-author Ron Kwok notes: Arctic snow depth, sea ice thickness, and volume are three very challenging measurements to obtain. The key takeaway for me is the remarkable loss of Arctic winter sea ice volume — one-third of the winter ice volume lost over just 18 years — that accompanied a widely reported loss of old, thick Arctic sea ice and decline in end-of-summer ice extent.

And the bigger issue here is the loss of winter ice, which is thicker and more resistant to melting as opposed to seasonal ice that easily comes and goes. As the reservoir of older ice is depleted, the Arctic ice is more vulnerable to seasonal melting. Kacimi goes on to explain: Current models predict that by the mid-century we can expect ice-free summers in the Arctic, when the older ice, thick enough to survive the melt season is gone.

This work is published in Geophysical Research Letters, and frankly, is terrible news.

More Information

AGU press release

“Arctic Snow Depth, Ice Thickness, and Volume From ICESat-2 and CryoSat-2: 2018–2021,” Sahra Kacimi and Ron Kwok, 2022 March 10, Geophysical Research Letters